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Tagamet belongs to a class of histamine blockers used mainly to treat gastrointestinal ulcers. The histamine blocking action prevents the stomach from producing excess acid, allowing the body to heal the ulcer.

If this medication works for you, improvement should be noticed within 4-6 weeks. Longer term use may be suggested by your doctor depending on your condition, and how long it takes to heal or prevent a recurrence. Stopping treatment abruptly could lead to a relapse. Only stop treatment on the advice of your doctor, once they're sure that the underlying condition has improved.

It's prescribed for prevention and treatment of peptic, duodenal, and gastric ulcers, ulcers caused by stress, excessive stomach acid production, acid reflux, upper gastrointestinal bleeding, in combination with antibacterials to relieve ulcer caused by Helicobacter pylori, and heartburn.

The drug may also be used in some cases to treat recurrent warts, acne, hives, shingles, and hyperthyroid conditions. It may further be effective in treating gastrointestinal ulcers caused by certain arthritis treatments.

Tagamet is only available by prescription, though an over the counter version is available (Tagamet HB) in a milder formulation that has fewer side effects. The over the counter version should not be used to treat ulcers, it's only intended to treat heartburn.

Tagamet Side Effects

Mild Side Effects: Allergic reaction (hives, rash), depression, diarrhea, headache, joint pain, muscle pain. These effects range from infrequent to rare, speak to your doctor if any side effect is bothersome.

Serious Side Effects: Allergic reaction (anemia, dermatitis, pancreatitis, serious rash), anaphylactic shock, bone marrow depression, bronchospasm, confusion, decreased platelets, hallucination, heart rhythm changes (slow heartbeat, ventricular black), liver damage, nervousness, worsened Alzheimer's. These side effects range from rare to extremely rare (case reports only), though any sign of them should be treated immediately by your physician. Seek emergency assistance if your condition is severe.

Cautions: This treatment may not be right for everyone, or you may have a condition that requires your doctor to make dosage adjustments. Inform your doctor of a history of any of the following to ensure that your treatment is as safe and effective as possible.

• Allergies: If you have, or have had in the past, an allergic reaction to this medication, you will not be able to continue to take it. Inform your physician of any food or dye allergies so that you can be prescribed an appropriate formulation.
• Anticoagulant Use: If you need to take any of these medications, you may need to take additional precautions or have the doses of one of the treatments altered.
• Aplastic Anemia: This medication may make the condition worse.
• Hemodialysis: This process decreases Tagamet's effectiveness, your doctor may recommend more frequent dosing.
• Kidney or Liver Impairment: Doses will have to be lowered.
• Low White Blood Cell or Platelet Counts: Your doctor will have to determine if this treatment is right for you.
• Phenylketonuria (PKU) - Some formulations may contain aspartame, which is not safe for this condition.
• Weak Immune System - The weaker stomach acid caused by this treatment may increase susceptibility to certain types of infection.

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This treatment should not be combined with all other types of over the counter or prescription medication. Speak with your doctor if you take, or plan to take, any of the following. If you see multiple physicians, make sure that each of them is fully informed of medication you have been prescribed by other doctors.

• Alcohol - Increases stomach acidity, avoid use until your doctor believes it's prudent to resume drinking.
• Antacids - Separate use according to your doctor's instructions, Tagamet may be less effective when used with these medications.
• Anticoagulants like Coumadin (warfarin) may build up in the body and cause increased bleeding unless more frequent INR testing and careful dosage adjustments are maintained.
• Anti-diabetic drugs or Insulin - This combination may result in undesirably low blood sugar and potentially seizures, regular testing for hypoglycemia is recommended.
• Antifungals like Diflucan (fluconazole), Nizoral (ketoconazole), Sporanox (itraconazole), and possibly others may be less effective when used with Tagamet. Take at least two hours apart, according to your doctor's instructions.
• Benzodiazepines (a class of antidepressants, anti-panic agents, sleep medications, and muscle relaxants) such as Ativan (lorazepam), Dalmane (flurazepam), Valium (diazepam), Halcion (triazolam), Librium(chlordiazepoxide), Restoril (temazepam), Xanax (alprazolam), Tranxene-SD (clorazepate), Paxipam (halazepam), ProSom (estazolam), Klonopin (clonazepam), and others, may have their effects increased by combined treatment. Your doctor may decrease your dose.
• Beta Blockers - Drugs like Blocadren (timolol), Cartrol (carteolol), Corgard (nadolol), Inderal (propranolol), Kerlone (betaxolol), Levatol (penbutolol), Lopressor (metoprolol), Normodyne (labetalol), Sectral (acebutolol), Sotacor (sotalol), Tenormin (atenolol), Trasicor (oxprenolol ), or Visken (pindolol) may build up and cause undesirably low heart rate and blood pressure.
• BiCNU (carmustine) - Severe bone marrow depression may occur.
• Bronchodilators of the xanthine (thioxanthine) class (Aminophylline, Dyphylline, Oxtriphylline, Somophyllin, Theo-Dur, etc...) - Effects may be increased, dosage adjustments may be necessary.
• Calcium channel blockers - Medications like Bepadin (bepridil), Calan (verapamil), Cardene (nicardipine), Cardizem (diltiazem), DynaCirc (isradipine), Nimotop (nimodipine), Plendil (felodipine), Procardia (nifedipine), or Sibelium (flunarizine) may build up and result in toxicity. A lower dose may be necessary.
• Chloroquine - Toxicity and possible cardiac arrest may result.
• Claritin (loratadine) - Claritin blood level may dramatically increase, doses should be lowered.
• Clozaril (clozapine) - Increased blood levels may result in toxicity.
• Cordarone (amiodarone) - Effects may be increased.
• Coreg (carvedilol) - Toxicity may result.
• Dilantin (phenytoin) - Effects may be increased.
• Effexor (venlafaxine) - Effects may be increased, risk of serotonin system developing if blood levels of Effexor remain too high.
• Flomax (tamsulosin) - Toxicity due to increased blood levels may occur.
• Glucophage (metformin) - Effects may be increased.
• Hivid (zalcitabine) - Increased blood levels and toxicity may result, your doctor will likely lower your Hivid dosages.
• Iron salts will decrease Tagamet absorption.
• Kola nut - May increase stomach acid.
• Lamisil (terbinafine) - Effects may be increased.
• Lanoxin (digoxin) - Levels of this medication may be altered, your doctor may need to check blood levels and alter your dosages.
• Ma Huang - May increase stomach acid.
• Narcotic pain medication like Codeine, Demerol (meperidine), Buprenex (buprenorphine), Darvon (propoxyphene), Dilaudid (hydromorphone), MS Contin or Kadian (morphine), nalbuphine, OxyContin (oxycodone), Percocet (oxycodone and acetaminophen), Stadol (butorphanol), Talwin compound (pentazocine), or Vicodin (hydrocodone and acetaminophen), Vicoprofen (hydrocodone and ibuprofen) may show increased central nervous system or respiratory (breathing) depressant effects. Consult your doctor for advice on how to take these medications together safely.
• Non-Steroidal Anti-Inflammatories, or NSAIDs, such as Butazolidine (phenylbutazone), Clinoril (sulindac), Ibuprofen (Motrin), Indocin (indomethacin), Naprosyn (naproxen), Toradol (ketorolac), and others, may be less effective when used with Tagamet.
• Procan (procainamide) - Effects may be increased.
• Prograf (tacrolimus) - This medication may build up to toxic levels when used with Tagamet.
• Propulsid (Cisapride) - Levels of this medication may increase, with potentially serious increases in heart rate.
• Protease inhibitors such as Agenerase (amprenavir), Norvir (ritonavir), and perhaps others, may lead to higher levels of Tagamet in the body.
• Quinaglute (quinidine) - Effects may be increased.
• Rapamune (sirolimus) - This medication may build up to toxic levels when used with Tagamet.
• Sandimmune (cyclosporine) - May build up to toxic levels.
• Selective serotonin reuptake inhibitors (SSRIs) like Celexa (citalopram), Paxil (paroxetine), Prozac (fluoxetine), Luvox (fluvoxamine), or Zoloft (sertraline) may have their effects increased by Tagamet. Your doctor may prescribe a dosage adjustment to prevent increased or unwanted side effects like serotonin syndrome.
• Sonata (zaleplon) - This medication may become toxic in combination, your doctor may lower your dosage.
• St. John's Wort - Combination may increase sun sensitivity.
• Tambocor (flecainide) - Effects of this medication may be increased, dosage adjustments and increased blood level checks may be necessary.
• Tegretol (carbamazepine) - Doses may need to be decreased, Tegretol may build up to toxic levels.
• Tetracycline antibiotics may decrease the Tagamet's effectiveness. Be sure to notify your doctor if you're taking any antibiotics, or if you should develop a need to take them during treatment.
• Tikosyn (dofetilide) - This medication may become toxic, lower doses may be needed.
• Trental (pentoxifylline) - Blood levels may be altered, your doctor may need to adjust your dose.
• Tricyclic antidepressants such as Elavil (amitriptyline), Asendin (amoxapine), Anafranil (clomipramine), Pertofrane or Norpramin (desipramine), Sinequan (doxepin), Tofranil (imipramine), Aventyl or Pamelor (nortriptyline), Vivactil (protriptyline), and Surmontil (trimipramine), may have increased effects when used with Tagamet. Your doctor may decrease your dosage.
• Viagra (sildenafil) - Blood levels of Viagra may increase drastically, speak to your doctor if you plan to take both treatments together.
• Zomig (zolmitriptan) - May build up to toxic levels, speak to your doctor about combining safely or finding a migraine treatment that doesn't interact with Tagamet.

Prescription Tagamet comes in the following forms:

• 200 mg tablet, round, printed with 'TAGAMET', '200', and 'SKF.'
• 300 mg tablet, round, printed with 'TAGAMET', '300', and 'SKF.'
• 400 mg tablet, oval, scored, embossed with 'TAGAMET', '400', and 'SB.'
• 800 mg tablet, oval, scored, embossed with 'TAGAMET', '800', and 'SB.'

Typical adult doses are as follows, keep in mind that these are just guidelines. Your doctor may suggest a different dosage or schedule according to your individual needs.

• Acid indigestion, heartburn, sour stomach: 100-200 mg with water an hour before consuming food or drink that normally cause symptoms.
• Active duodenal or gastric ulcer: 300 mg four times daily, with meals and at bedtime. Alternate dosing schedules include: two 400-600 mg doses, on waking and at bedtime; or 800 mg at bedtime.
• Duodenal ulcer prevention: 300 mg twice daily, or 400 mg at bedtime.
• Gastroesophageal reflux (acid reflux) disease: 800-1600 mg daily, in divided doses as suggested by your doctor.
• Stomach produces too much acid: 300 mg four times daily, with meals and at bedtime.

Take Tagamet after meals, when digestive acids are being produced at their highest rates. Take your medication as soon as you remember if you should forget a dose, but don't double doses. If it's almost time for your next dose, skipped the missed amount. Speak to your doctor if you find that you forget to take your medication frequently.

This medication may cause some confusion or dizziness, especially if you are over 50. Do not engage in potentially hazardous activities until you are familiar with your reaction to the medication.

The oral suspension form should be shaken thoroughly before measuring. Do not allow it to freeze, store as recommended on the packaging.

Store Tagamet away from direct light and heat. Store in a dry location; avoid storing it in the bathroom, near sinks, or other areas where it may become damp. Do not use after the expiration date.

Keep Tagamet away from children; both when storing it, and when discarding any unused medication.

Tagamet and Pregnancy

Tagamet has not been demonstrated to cause birth defects or miscarriage in pregnant women, though adequate studies have not been performed. Speak with your doctor if you are pregnant, or plan to become pregnant during treatment.

This medication should not be combined with breastfeeding, it may cause undesirable side effects in infants.

Tagamet and Children

This drug does not appear to cause different side effects in children than in adults with short term use. For children 12 and under, dosage will be determined by body weight. Teenagers will usually be prescribed the adult dose.

Long-term use is not recommended, as this has not been adequately studied.

Tagamet and Seniors

Confusion and dizziness are more likely, half the usual dose may be prescribed.

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Tagamet is a trademark of GlaxoSmithKline

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The information contained in this document is provided for educational purposes and information only. It is not a substitute for consultation with a physician or Health professional, either to diagnose symptoms or prescribe treatment. Any dosages mentioned are general guidelines only, please follow the directions of your doctor or pharmacist exactly when taking medication. We have made every effort to ensure that this information is accurate, but only your doctor, physician or Health professional can say if a medication, a drug alternative or drug combination, is safe for you. Information intended for US residents only.